# frozen_string_literal: true

module MalawiHivProgramReports
  module Pepfar
    ##
    # Patients who started TPT just before the start of the current
    # and have finished within the current reporting period.
    class TbPrev2
      attr_reader :start_date, :end_date

      include Utils

      def initialize(start_date:, end_date:, **_kwargs)
        @start_date = ActiveRecord::Base.connection.quote(start_date)
        @end_date = ActiveRecord::Base.connection.quote(end_date)
      end

      def find_report
        report = init_report
        patients = group_patients_by_tpt_course(patients_on_tpt)

        load_patients_into_report(report, patients.six_h, '6H') do |patient|
          # 6H has a constant dosage of 1 pill per day
          patient['total_pills_taken'].to_i >= FULL_6H_COURSE_PILLS
        end

        load_patients_into_report(report, patients.three_hp, '3HP') do |patient|
          # 3HP daily dosages vary by patient weight can't use easily use pills
          # to determine course completion
          patient['total_days_on_medication'].days >= FULL_3HP_COURSE_DAYS
        end

        report
      end

      private

      FULL_6H_COURSE_PILLS = 168
      FULL_3HP_COURSE_DAYS = (28.days - 1.day) + (56.days - 1.day) # 82 Days
      # NOTE: Arrived at 82 days above from how 3HP is prescribed. 1st time prescription
      #       is 1 month (28 days) then 2 months (56 days). And we assume that patients
      #       start taking medication the very same they are given thus we subtract 1.

      def init_report
        pepfar_age_groups.each_with_object({}) do |age_group, report|
          report[age_group] = %w[M F Unknown].each_with_object({}) do |gender, gender_sub_report|
            gender_sub_report[gender] = %w[6H 3HP].each_with_object({}) do |tpt, tpt_sub_report|
              tpt_sub_report[tpt] = {
                started_new_on_art: [],
                started_previously_on_art: [],
                completed_new_on_art: [],
                completed_previously_on_art: []
              }
            end
          end
        end
      end

      def load_patients_into_report(report, patients, tpt, &patient_has_completed_tpt)
        patients.each do |patient|
          age_group = patient['age_group']
          gender = patient['gender']&.first&.upcase || 'Unknown'
          tpt_states = find_patient_tpt_state(patient, &patient_has_completed_tpt)

          tpt_states.each do |tpt_state|
            report[age_group][gender][tpt][tpt_state] << patient
          end
        end
      end

      def find_patient_tpt_state(patient, &patient_has_completed_tpt)
        if patient_has_completed_tpt[patient]
          return %i[started_new_on_art completed_new_on_art] if patient_new_on_art?(patient)

          return %i[started_previously_on_art completed_previously_on_art]
        end

        return %i[started_new_on_art] if patient_new_on_art?(patient)

        %i[started_previously_on_art]
      end

      def patient_new_on_art?(patient)
        tpt_initiation_date = patient['tpt_initiation_date'].to_date
        art_start_date = patient['art_start_date'].to_date

        (tpt_initiation_date >= art_start_date) && (tpt_initiation_date < art_start_date + 90.days)
      end

      def patients_on_tpt
        ActiveRecord::Base.connection.select_all <<~SQL
          SELECT person.person_id AS patient_id,
                 patient_identifier.identifier AS arv_number,
                 DATE(MIN(orders.start_date)) AS tpt_initiation_date,
                 date_antiretrovirals_started(person.person_id, MIN(patient_state.start_date)) AS art_start_date,
                 SUM(drug_order.quantity) AS total_pills_taken,
                 SUM(DATEDIFF(orders.auto_expire_date, orders.start_date)) AS total_days_on_medication,
                 person.gender,
                 person.birthdate,
                 disaggregated_age_group(person.birthdate, DATE(#{end_date})) AS age_group,
                 GROUP_CONCAT(DISTINCT orders.concept_id SEPARATOR ',') AS drug_concepts
          FROM person #{current_partition}
          LEFT JOIN patient_identifier #{current_partition}
            ON patient_identifier.patient_id = person.person_id
            AND patient_identifier.voided = 0
            AND patient_identifier.identifier_type IN (SELECT patient_identifier_type_id FROM patient_identifier_type #{current_partition} WHERE name = 'ARV Number')
          INNER JOIN patient_program #{current_partition}
            ON patient_program.patient_id = person.person_id
            AND patient_program.program_id IN (SELECT program_id FROM program #{current_partition} WHERE name = 'HIV PROGRAM')
            AND patient_program.voided = 0
          INNER JOIN patient_state #{current_partition}
            ON patient_state.patient_program_id = patient_program.patient_program_id
            AND patient_state.state = 7 /* State: 7 == On antiretrovirals */
            AND patient_state.start_date < DATE(#{start_date})
            AND patient_state.voided = 0
          INNER JOIN encounter #{current_partition} AS prescription_encounter
            ON prescription_encounter.patient_id = patient_program.patient_id
            AND prescription_encounter.program_id IN (SELECT program_id FROM program #{current_partition} WHERE name = 'HIV PROGRAM')
            AND prescription_encounter.encounter_type IN (SELECT encounter_type_id FROM encounter_type WHERE name = 'Treatment')
            AND prescription_encounter.encounter_datetime >= DATE(#{start_date}) - INTERVAL 6 MONTH
            AND prescription_encounter.encounter_datetime < DATE(#{start_date})
            AND prescription_encounter.voided = 0
          INNER JOIN orders #{current_partition}
            ON orders.encounter_id = prescription_encounter.encounter_id
            AND orders.order_type_id IN (SELECT order_type_id FROM order_type #{current_partition} WHERE name = 'Drug order')
            AND orders.start_date >= DATE(#{start_date}) - INTERVAL 6 MONTH
            AND orders.start_date < DATE(#{start_date})
            AND orders.voided = 0
          INNER JOIN concept_name #{current_partition}
            ON concept_name.concept_id = orders.concept_id
            AND concept_name.name IN ('Rifapentine', 'Isoniazid', 'Isoniazid/Rifapentine')
          INNER JOIN drug_order #{current_partition}
            ON drug_order.order_id = orders.order_id
            AND drug_order.quantity > 0
          WHERE person.voided = 0
            AND person.person_id NOT IN (
               /* People who had a dispensation prior to the 3 to 9 months before start of reporting period.
                 Continuing medication after a 9 months break is considered a restart hence such patients
                 are classified as new on TPT.
               */
              SELECT DISTINCT encounter.patient_id
              FROM encounter #{current_partition}
              INNER JOIN orders #{current_partition}
                ON orders.encounter_id = encounter.encounter_id
                AND orders.concept_id IN (SELECT concept_id FROM concept_name #{current_partition} WHERE name IN ('Rifapentine', 'Isoniazid') AND voided = 0)
                AND orders.order_type_id IN (SELECT order_type_id FROM order_type #{current_partition} WHERE name = 'Drug order')
                AND orders.start_date < DATE(#{start_date}) - INTERVAL 6 MONTH
                AND orders.start_date >= DATE(#{start_date}) - INTERVAL 15 MONTH
                AND orders.voided = 0
              INNER JOIN drug_order #{current_partition}
                ON drug_order.order_id = orders.order_id
                AND drug_order.quantity > 0
              WHERE encounter.program_id IN (SELECT program_id FROM program #{current_partition} WHERE name = 'HIV PROGRAM')
                AND encounter.encounter_type IN (SELECT encounter_type_id FROM WHERE name = 'Treatment')
                AND encounter.encounter_datetime < DATE(#{start_date}) - INTERVAL 6 MONTH
                AND encounter.encounter_datetime >= DATE(#{start_date}) - INTERVAL 15 MONTH
                AND encounter.voided = 0
            ) AND person.person_id NOT IN (
            /* External consultations */
            SELECT DISTINCT registration_encounter.patient_id
            FROM patient_program #{current_partition}
            INNER JOIN program #{current_partition} ON program.name = 'HIV PROGRAM'
            INNER JOIN encounter #{current_partition} AS registration_encounter
              ON registration_encounter.patient_id = patient_program.patient_id
              AND registration_encounter.program_id = patient_program.program_id
              AND registration_encounter.encounter_datetime < DATE(#{end_date}) + INTERVAL 1 DAY
              AND registration_encounter.voided = 0
            INNER JOIN (
              SELECT MAX(encounter.encounter_datetime) AS encounter_datetime, encounter.patient_id
              FROM encounter #{current_partition}
              INNER JOIN encounter_type
                ON encounter_type.encounter_type_id = encounter.encounter_type
                AND encounter_type.name = 'Registration'
              INNER JOIN program #{current_partition}
                ON program.program_id = encounter.program_id
                AND program.name = 'HIV PROGRAM'
              WHERE encounter.encounter_datetime < DATE(#{end_date}) AND encounter.voided = 0
              GROUP BY encounter.patient_id
            ) AS max_registration_encounter
              ON max_registration_encounter.patient_id = registration_encounter.patient_id
              AND max_registration_encounter.encounter_datetime = registration_encounter.encounter_datetime
            INNER JOIN obs #{current_partition} AS patient_type_obs
              ON patient_type_obs.encounter_id = registration_encounter.encounter_id
              AND patient_type_obs.concept_id IN (SELECT concept_id FROM concept_name #{current_partition} WHERE name = 'Type of patient' AND voided = 0)
              AND patient_type_obs.value_coded IN (SELECT concept_id FROM concept_name #{current_partition} WHERE name IN ('Drug refill', 'External consultation') AND voided = 0)
              AND patient_type_obs.voided = 0
            WHERE patient_program.voided = 0
          )
          GROUP BY person.person_id
        SQL
      end

      ##
      # Groups patients into their TPT categories (ie 6H and 3HP) based on their drugs
      #
      # Returns an object with a three_hp and six_h methods, each of which
      # is an array of patients for that category.
      def group_patients_by_tpt_course(patients)
        patients.each_with_object(OpenStruct.new(six_h: [], three_hp: [])) do |patient, categories|
          if patient_on_3hp?(patient)
            categories.three_hp << patient
          else
            categories.six_h << patient
          end
        end
      end

      def patient_on_3hp?(patient)
        drug_concepts = patient['drug_concepts'].split(',').collect(&:to_i)
        drug_concepts.intersect?([rifapentine_concept.concept_id, isoniazid_rifapentine_concept&.concept_id])
      end

      def rifapentine_concept
        @rifapentine_concept ||= ::ConceptName.find_by!(name: 'Rifapentine')
      end

      def isoniazid_rifapentine_concept
        @isoniazid_rifapentine_concept ||= ::ConceptName.find_by!(name: 'Isoniazid/Rifapentine')
      end
    end
  end
end